1. Field of the Invention
This invention relates to a pull-start engine, and more particularly to a pull-start engine that includes a lubricating unit.
2. Description of the Related Art
Referring to FIG. 1, a conventional pull-start engine includes a crankcase unit 11, a pull-start unit 12, a gearbox unit 13, a first conduit unit 14, a second conduit unit 14′, and a starter motor 15. Normally, the engine is started by means of the starter motor 15. When a battery unit (not shown) for providing electricity to the starter motor 15 is fully discharged, or when the starter motor 15 malfunctions, the pull-start unit 12 can be used to start the engine.
The crankcase unit 11 includes a crankcase 111, and a crankshaft 112 journalled within the crankcase 111 and formed with a lubricant passage 113 that permits a lubricant to flow therein for lubricating and dissipating heat from the crankshaft 112.
The pull-start unit 12 is disposed rotatably on the crankcase 111, and is operable to rotate the crankshaft 112 to thereby start the engine. A surrounding wall 121 of the pull-start unit 12 is sleeved fixedly on an end of the crankshaft 112 of the crankcase unit 11.
The gearbox unit 13 includes a gearbox 131 connected fixedly to the crankcase 111 of the crankcase unit 11, and a drive shaft 132 journalled within the gearbox 131. The drive shaft 132 is formed with a lubricant passage 133 that is communicated with the second conduit unit 14′ and that permits the lubricant to flow therein for lubricating and dissipating heat from the drive shaft 132.
The first conduit unit 14 is disposed in the crankcase unit 11. The lubricant is fed into one end portion of the lubricant passage 113 in the crankshaft 112 via the first conduit unit 14, and then flows from the other end portion of the lubricant passage 113 in the crankshaft 112 into the lubricant passage 133 in the drive shaft 132 via the second conduit unit 14′.
As a result, a significant amount of time is necessary for the lubricant to reach the lubricant passage 133 in the drive shaft 132. Furthermore, since heat is transferred from the crankshaft 112 to the lubricant during flow of the lubricant in the lubricant passage 113 in the crankshaft 112, when the lubricant reaches the lubricant passage 133 in the drive shaft 132, the temperature of the lubricant is high, thereby reducing the heat dissipating effect.